Pancreatic adenocarcinoma is the fourth most common cause of cancer death in the United States and usually diagnosed at an advanced state. Poor clinical outcomes could be due, at least in part, to the fact that conventional therapies are directed at tumor cells, instead of targeting the cancer stem cell population. Emerging evidence showed that the Cancer Stem Cells (CSCs) is responsible for the disease aggressiveness, metastasis, and resistance to therapy in several cancers including pancreatic cancer. It is important need to identify a cancer stem cell maintenance marker to understand the cancer stem cells and to eradicate the tumors in patients. To date, few putative cancer stem cell markers (i.e. CD44, CD24, ALDH1 and CD133) have been identified. Considerable research efforts have been directed toward the identification of specific cancer stem cell maintenance markers including those of pancreatic cancer. In search of a new marker with functional significance in pancreatic cancer CSCs, we have focused on the pancreatic differentiation 2/polymerase association factor 1 or (PD2/Paf1). Interestingly, I have demonstrated that Paf1/PD2 plays a major role in the maintenance of self-renewal by interacting with Oct3/4 in mouse embryonic stem cells. In the preliminary results I have shown overexpression of PD2/Paf1 in pancreatic CSCs and its knockdown leads to reduce CSC phenotype and drug resistance property. These findings have prompted us to analyze the contributions of PD2/Paf1 on pancreatic CSC. The proposed hypothesis of this application is that the PD2/Paf1 is overexpressed in pancreatic cancer stem cells and plays a major role in the self-renewal and drug resistance in CSCs. To test our hypothesis, I propose the following aims: Aim #1 is to analyze the CSC population and PD2/Paf1 in genetically engineered mouse progression model of pancreatic cancer. I will analyze the CSC population along with PD2/Paf1 expression in the progression of PC. These results will answer the questions (i) whether CSC population arise in early stage? (ii) how is it involved in the progression of PC?; and (iii) what is the role of PD2/Paf1 during PC progression? Aim #2 is to investigate the role of PD2/Paf1 in clonogenic variation and lineage differentiation in pancreatic cancer stem cells. We will isolate different clonogenic CSCs by different marker and analyze the importance of PD2/Paf1 in clonogenicity. We will also analyze the lineage differentiation potential of these CSCs by matrigel differentiation assay. Aim #3 is to understand the function and mechanism(s) of PD2/Paf1 in self-renewal and drug resistance of pancreatic CSCs. The relationship between self-renewal gene Shh and drug resistance gene MDR2 will be examined by immunoprecipitation and ChIP analysis. The main innovation and impact of the study are the identification of pancreatic cancer stem cell specific novel marker PD2/Paf1 and its role in CSC maintenance would provide critical information for the long-term goal of developing novel targeted therapy for PC-CSCs which will help to manage this lethal disease.